1. Field of the Invention
The invention relates to a cooling apparatus for an internal combustion engine, in which a coolant is circulated in an engine cooling system by operating a water pump, a method of controlling the cooling apparatus, and a hybrid vehicle including the cooling apparatus.
2. Description of the Related Art
A cooling apparatus for an internal combustion engine generally includes an engine cooling system that includes a water jacket formed in the engine, a radiator that is a heat exchanger, and a circulation passage that connects the water jacket and the radiator (for example, refer to Japanese Patent Application Publication No. 2007-218115 (JP-A-2007-218115)). The cooling apparatus for an internal combustion engine also includes a water pump that pressurizes and delivers a coolant with which the engine cooling system is filled. The coolant is forcibly circulated in the engine cooling system, and thus, the internal combustion engine is cooled, by operating the water pump.
For example, in the case where the internal combustion engine is assembled or the coolant is changed, when the coolant is supplied into the engine cooling system, an operation for removing air that has entered the engine cooling system (so-called an air bleeding operation) may not be sufficiently performed. In such a case, there may be air in the engine cooling system, and accordingly, a delivery capacity of the water pump may be decreased.
Particularly, when there is a large amount of gas in the engine cooling system, the delivery capacity of the water pump is greatly decreased. Therefore, the coolant may not be appropriately circulated in the engine cooling system. In some cases, the internal combustion engine may be overheated due to a decrease in cooling performance caused by an insufficient amount of the coolant delivered by the water pump.